A244986 a(n) = Position of 2^n among the numbers which are divisible by the square of their highest noncomposite factor (i.e., the union of {1} and A070003), 0 if not there.

1, 0, 2, 3, 5, 9, 14, 23, 37, 58, 90, 143, 225, 355, 563, 894, 1426, 2277, 3643, 5839, 9398, 15155, 24518, 39758, 64607, 105250, 171874, 281237, 461255, 758040, 1248270

Offset

0,3

Links

Table of n, a(n) for n=0..30.

Formula

For all n >= 1, a(n+1) = A244984(A006254(n)).

Example

2 is not divisible by 2^2, thus a(2) = 0, the only zero in the sequence.
2^4 = 16 is the fifth term in [1, 4, 8, 9, 16, 18, 25, 27, 32, 36, ...] (the union of {1} and A070003), thus a(4) = 5.
2^5 = 32 is the ninth term in the same list, thus a(5) = 9.

Crossrefs

From a(2) onward one more than A244985.

Cf. A000079, A070003, A006254, A244984.

Sequence in context: A056686 A326332 A079962 * A293547 A124502 A251572

Adjacent sequences: A244983 A244984 A244985 * A244987 A244988 A244989

Keyword

nonn

Author

Antti Karttunen, Jul 21 2014

Status

approved